Horm Metab Res 2018; 50(07): 562-567
DOI: 10.1055/a-0630-1529
Endocrine Care
© Georg Thieme Verlag KG Stuttgart · New York

Relation of RANKL and OPG Levels with Bone Resorption in Patients with Acromegaly and Prolactinoma

Firuzan Firat Ozer
1  Hacettepe Medical School, Department of Endocrinology and Metabolism, Hacettepe University, Ankara, Turkey
,
Selcuk Dagdelen
1  Hacettepe Medical School, Department of Endocrinology and Metabolism, Hacettepe University, Ankara, Turkey
,
Tomris Erbas
1  Hacettepe Medical School, Department of Endocrinology and Metabolism, Hacettepe University, Ankara, Turkey
› Author Affiliations
Further Information

Publication History

received 28 March 2018

accepted 03 May 2018

Publication Date:
12 June 2018 (online)

Abstract

The objective of this study was to investigate the effect of hyperprolactinemia and high levels of insulin-like growth factor-I (IGF-I) on bone resorption and their relation with receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG) in patients with prolactinoma and acromegaly. Thirty-one patients with acromegaly, 28 patients with prolactinoma, and 33 healthy individuals were included in the study. Serum concentrations of RANKL, OPG, bone alkaline phosphatase (bone ALP), osteocalcin (OC), C-terminal telopeptide of type 1 collagen (CTX), procollagen type 1 N-terminal propeptide (P1NP) and urine deoxypyridinoline (DPD) levels were detected and bone mineral density (BMD) was measured. Groups were not statistically different from each other with regard to serum levels of RANKL and OPG. The RANKL/OPG ratio was higher in the prolactinoma group than in the control group (p=0.046). A positive correlation between OPG and increasing age was detected in both the prolactinoma and control groups (r=0.524, p=0.004 and r=0.380, p=0.029, respectively). An inverse correlation was observed between IGF-I and OPG after excluding age in the prolactinoma group (r=–0.412, p=0.046). OC and bone ALP were negatively associated with RANKL in the acromegaly group (r=–0.384, p=0.036 and r=–0.528, p=0.003, respectively). There was an inverse correlation between OPG and BMD at the femoral neck in the acromegaly group (r=–0.422, p=0.02). The effect of IGF-I on bone remodeling may be partly mediated by RANKL and OPG. The RANKL/OPG ratio plays an important role in prolactinoma. A positive correlation of OPG with age and an inverse correlation with IGF-I favor the compensatory response of OPG against bone loss in the aging skeleton.